Sorry, I mean turnout, what is their turnout number, has to be low.
Actually, their turnout rate is pretty high, but lots are ineligible to vote because they are in or out of prison.
Look at this fascinating page I found that shows that, plus the usual turnout differences by age and a dramatic graph of the difference by education level. Given the education differential, I’d guess that eligible blacks outperform other groups by voting at the lower education levels. (Maybe because there is so much inner-city voting corruption?)
http://www.electproject.org/home/voter-turnout/demographics